Mass screenings for cervical cancer in Finland 1963-71. Organization, extent, and epidemiological implications.

In Finland, up to 100,000 smears are taken annually from Finnish women, who number more than 2 millions, in conjunction with the mass screening programme organized by the Cancer Society of Finland. About 400,000 smears were taken during the period 1963-71; the detection rates per 10(5) were found to be 69 for invasive cancer, 6 for microinvasive carcinoma, 168 for carcinoma in situ, 127 for dysplasia of high degree. Those previously married, and those experiencing bleeding on sexual intercourse, formed high risk groups (relative risk 2 and 6) whereas those previously electro-coagulated had a relative risk of 0.13 only. Probably no changes will occur in the time trends of mortality rates as a result of the screening. The incidence of invasive carcinomas was found to be decreasing by time, although the increase in carconoma in situ cases exceeded this decline.